Radius-plate assembly

ABSTRACT

An assembly for reducing a fracture between an epiphysis and a diaphysis of a bone has a bone plate having a fan-shaped outer end formed with a plurality of outer holes and a bar-shaped inner end extending along a longitudinal axis from the outer end and formed with a plurality of inner holes. The plate further is formed on the bar-shaped inner end with a longitudinally extending throughgoing guide slot and between the guide slot and the outer holes with an aperture. A slide has a longitudinally extending leg with an inner end formed with a guide formation engaged into and longitudinally slidable along the guide slot and a crosspiece overlying the aperture and engaging the bone plate to both transverse sides of the aperture. The crosspiece is formed with a transversely elongated slide slot, and a slide screw engaged through the slide.

FIELD OF THE INVENTION

The present invention relates to a bone plate. More particularly thisinvention concerns a bone-plate assembly used to secure the epiphysis orouter end of a long bone such as the radius to the bone's diaphysis orshaft.

BACKGROUND OF THE INVENTION

A typical bone plate such as described in WO 2004/089233 of Thielke, US2006/0229619 of Orbay, US 2006/0235404, or US 2007/0055253 all of Orbay,extends along an axis and has an outer end that is fan-shaped and formedwith an array of holes so that it can be solidly screwed to theepiphysis to one side of the fracture or other injury that is to bereduced so the bone can grow back together. Extending from thisfan-shaped outer end is a flat narrow bar formed with another array ofholes allowing it to be screwed to the bone's diaphysis. The most commonuse of such a bone plate is in setting or reducing a distal fracture ofthe radius, but it can of course also be used for any type of fractureon a distal portion of a long bone.

Because of the presence of tendons and ligaments, reducing such a breakis difficult, especially considering that the more tightly the two boneparts can be engaged together the more quickly arthrodesis will mend thefracture.

The problem with such a plate is that it allows little or no adjustmentonce secured in place. The system of US 2007/0233114 of Bouman hastransverse and longitudinal slots allowing some longitudinal andtransverse shifting of parts, but in a structure intended for use on abone shaft. It is known to form the inner bar-shaped part of the platewith an axially extending slot to allow the epiphysis and the bone plateto be shifted limitedly longitudinally of the bone to close up afracture. Thus the orthopedic surgeon fixes the plate on the distalfragment, installs a screw loosely in the slot and pushes the distalfragment back into contact with the proximal portion of the bone,thereby making the screw slide in the hole up to the point where the twobone parts come in direct abutment with one another. In this position ofthe plate, the screw extending loosely through the longitudinal slot istightened to lock in the set position.

The surgeon therefore cannot correct a transverse positioning defect,except if he redrills the proximal fragment near the first hole at anoffset. In practice, this is often impossible since the two holes wouldbe too close to one another. Therefore the transverse defect is normallyleft uncorrected so that the outer end of the plate overextends on theside, which can be unattractive and can cause patient discomfort.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide animproved bone-plate assembly usable to reduce a fractured radius.

Another object is the provision of such an improved radius plate thatovercomes the above-given disadvantages, in particular that allowstransverse adjustment of the epiphysis relative to the diaphysis.

A further object is to provide a surgical method of using such anassembly.

SUMMARY OF THE INVENTION

An assembly for reduction of a fracture between an epiphysis and adiaphysis of a bone has according to the invention a bone plate having afan-shaped outer end formed with a plurality of outer holes and abar-shaped inner end extending along a longitudinal axis from the outerend and formed with a plurality of inner holes. The plate is adapted tobe screwed through the outer holes to the epiphysis and through theinner holes to the diaphysis. The plate further is formed on thebar-shaped inner end with a longitudinally extending throughgoing guideslot and between the guide slot and the outer holes with an aperture ofa predetermined transverse width and of a longitudinal length generallyequal to a length of the guide slot. A slide has a longitudinallyextending leg with an inner end formed with a guide formation engagedinto and longitudinally slidable along the guide slot and a crosspieceoverlying the aperture and of a transverse width at least equal to thetransverse width of the aperture such that crosspiece engages the boneplate to both transverse sides of the aperture. The crosspiece is formedwith a transversely elongated slide slot, and a slide screw engagedthrough the slide.

Once the plate is in the correct position, the surgeon can then set theanchor screws in place in the inner and outer holes, for example withthe aid of a screw/drill guide, with no risk of moving, then remove thedetachable adjuster.

Therefore, although the system is complicated by the addition of adetachable element, perfect positioning is is achieved.

In particular embodiments of the invention, one and/or the otherfollowing features are relevant:

-   -   the inner part is extends in a first plane and the outer part in        a second plane inclined with respect to the plane of said inner        part, for example by a few degrees, for example 5° to 15°,        advantageously between 8° and 10°. This way, the T-slide also is        form with a slight elbow and the guide pin a sufficient height        to ensure guiding during the longitudinal adjustment;    -   the length of the guide slot is between 6 mm and 12 mm,        advantageously on the order of 10 mm;    -   the length of the slide slot is between 12 mm and 14 mm.    -   the width of the aperture is about 5 mm at its inner end and the        order of 12 mm or more at its outer end;    -   the substantially triangular aperture has a surface area        comprised between half and ⅘th of the enlarged base of the outer        part.

The system further comprises a guide for the epiphysial screws havingguide holes alignable with the outer holes for the anchor screws of theouter part.

The method according to the invention has the steps of first screwingthe outer part to the epiphysis through the outer holes to anchor thebone plate to the epiphysis and then screwing the slide screw throughthe slide slot and aperture into the diaphysis to press the adjusteragainst the bone plate and press the bone plate against the bone. Thenthe bone plate and the epiphysis it is anchored to are shiftedlongitudinally relative to the diaphysis with sliding of the pivotformation in the guide slot to reduce the fracture and transverselyrelative to the diaphysis with to correct transverse offset of thediaphysis and epiphysis at the fracture. The result can be perfectalignment without having to reset any screws.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 is a top view of a plate according to the invention on an end ofa fractured radius;

FIG. 2 shows the same plate and the detachable adjuster of the systemaccording to the invention;

FIG. 3 shows the system with a further guide for epiphysial screwing;

FIGS. 4A to 4C show the system of FIG. 2 in three different positions,showing the longitudinal adjustability according to the invention; and

FIGS. 5A to 5C show the system of FIG. 2 in three different positions,showing the transverse adjustability according to the invention.

SPECIFIC DESCRIPTION

As seen in FIG. 1 a system S comprises a metal plate 1 having afan-shaped outer part 2 for reducing a fracture F between a fractureddistal end portion A of a radius and the shaft B of this bone. The plate1 is formed with outer holes 3 for anchoring it by means of screws 22(FIGS. 4A-5C), for example eight holes 3 in two rows of predetermineddimensions and at specific places on the end of the fan-shaped outerpart 2 as is known per se. The plate 1 also is unitarily formed of anelongated bar-shaped inner part 4 extending along a longitudinal axis 14and provided with second holes 5, for example two holes for respectiveunillustrated anchor screws also known per se. The inner part 4 isfurther formed with an elongated, throughgoing, and longitudinallyextending slot 6, for adjusting position of the plate 1 on the radius A,B parallel to the axis 14.

Here as visible in FIG. 3 the outer paddle- or fan-shaped end 2 liesgenerally in a plane forming an obtuse angle of between 165° and 5° to aplane of the narrow stem or inner part 4 of the plate 1.

According to the invention, the outer part 2 further has an innerportion 7 of generally trapezoidal shape and fixed to the outer end 4′of the inner part 4. It is formed with a substantially triangular ortrapezoidal aperture 8.

As shown in FIG. 2, the system S further comprises a movable T-shapedadjuster slide 9 having a longitudinally extending leg 10 of a width 1′in an outer region 12 greater by about 2 mm than a width 1 of theparallel-sided slot 8. The leg 10 also has an inner end 11 of a widthnarrower than the region 12. The inner end 11 of the leg 10 is providedwith a guide pin 28 (FIG. 4B) slidable along the slot 6. This guide pin28 is basically cylindrical and stepped with an inner end fittingslidably in the slot 6 to allow easy longitudinal sliding of theadjuster 9 on the plate 1 while still allowing as described below theadjuster 9 to pivot about an axis of the pin 28.

The T-shaped adjuster 9 further has a crosspiece 13 having a transversewidth L′ measured perpendicular to the longitudinal direction or axis 14of the slot 6 or of the leg 10. This dimension L′ is greater than amaximum transverse width L of the aperture 8. The crosspiece 13 has ends15 that are thus in contact over a sufficient distance, for example afew millimeters, with outer edges 16 of the aperture 8 of the enlargedouter part 2.

Furthermore, the crosspiece 13 is formed with a transversely elongatedslot 17 with parallel, stepped, and straight inner and outer edges andcircularly rounded ends. The transverse length of this slot 17 issubstantially equal to the transverse width L of the aperture 8. Thisslot 17 is traversed generally centrally by a positioning screw 18 thatis set in the diaphysial bone part B in a region much wider than thediameter of the screw 18. The head of this screw 18 bears downward, thatis toward the bone on shoulders of the side of the slot 17 so this screw18 secures the adjuster 9 in place against the bone plate 1 and alsoholds the inner part 4 of the plate 1 flatly against the diaphysis B.Thus the plate 1 can move transversely of the screw 18 set in thediaphysis B, just as longitudinal displacement of the pin 28 along theslot 6 allows for longitudinal displacement of the plate 1 as describedmore precisely hereinafter with reference to FIGS. 4A-4C and 5A-5C.

FIG. 3 further shows a guide 19 for setting the epiphysial screws 22 andhaving cylindrical guide holes 20 aligned with the holes 3. The guide 19has a handle or rod 21 for positioning and maintaining the guide 19 inposition during drilling of the pilot holes for the screws 22.

FIGS. 4A to 4C show how the longitudinal adjustment is done.

Here, the function of the T-shaped slide 9 is to adjust the longitudinalspacing between the portions A and B before or after the epiphysialscrews 22 have been set to anchor the outer part 2 solidly on the outerbone part A. The degree of longitudinal adjustment is equal to thelongitudinal length of the slot 6 minus the diameter of the part of theguide pin 28 engaged in the slot 6.

FIG. 4A shows a first position in which the guide pin 28 of the leg 10of the T-shaped adjuster 9 abuts an outer end 23 of the slot 6. Thefractured distal end or epiphysis A of the radius is meanwhile fixed byone or two of the screws 22 to the outer end 2 of the plate 1 to fix theplate 1 on the bone part A. In this end position, the fractured distalportion A of the radius is at a spacing x from the proximal portion B ofthe bone.

As the plate 1 is shifted inward relative to the adjuster 9 that islongitudinally fixed by the screw 18, this screw 18 shifts along theslot 6 (see FIG. 4B) outward in the direction of arrow 24 along with theslide 9 to bring the fractured portion A closer to the shaft part Buntil the spacing x as shown in FIG. 4C is completely eliminated and thefracture F is reduced, that is with the part A in direct contact at thefracture F with the proximal portion B of the bone.

If, however, it then appears that the transverse position is incorrect,that is the parts A and B are offset is transversely relative to at thefracture region F, this can be solved according to the invention asshown now in reference to FIGS. 5A and 5C that successively show aposition 25 offset transversely to one side, a centered position 26, andan oppositely transversely offset position 27.

Because the plate 1 can shift transversely relative to the pin 28engaged in the slot 27, the outer part 2 of the plate 1 secured by thescrews 22 to the fractured portion A can move transversely relative tothe elongated inner bone part B in such a way that it is in the desiredcentered position 26.

The overall procedure for setting in place an osteosynthesis systemaccording to the invention will now be described hereinafter withreference to FIG. 3.

After two or three of the epiphysial screws 22 have been inserted in theholes 20, a first control of the assembly S on the end of the radius iscarried out by x-ray.

According to the invention if, after the epiphysial screws 22 have beenfixed, the epiphysis/diaphysis position is not right, the position canbe corrected without disassembling the epiphysial zone.

To do so, with the screw 18 of the element 13 or slider loosened a bit,the plate 1 shifted transversely relative to the pin 18 for transversecorrection and slid along this pin 18 for longitudinal (axis 14)correction to the right position of the portions A and B relative toeach other. Then the screw 18 can be tightened to temporarily fix thisposition.

The other epiphysial screws are then inserted after the correct positionof the plate 1 has been found and two proximal diaphysial screws are setin the holes 5.

Finally, the screw 18 is taken out, the slide 9 is removed, and anotherdiaphysial screw is set in the slot 6 to solidly fix the plate 1 on bothparts A and B.

The slide 9 serves to adjust the position of the plate 1 before or afterthe first epiphysial screws 22 are set.

The degree of adjustment is related to the longitudinal dimension of theslot 6 for longitudinal mobility, and to the transverse dimension of theslot 17 of the crosspiece 13 for transverse mobility.

The slide 9 is removed at the end of the surgery before the surgicalfield is closed.

It goes without saying and it also results from what precedes that thepresent invention is not limited to the embodiments particularlydescribed. On the contrary, it encompasses all the alternatives andparticularly those where the slide 9 is, for example, triangular.

1. An assembly reducing a fracture between an epiphysis and a diaphysisof a bone, the assembly comprising: a bone plate having a fan-shapedouter end formed with a plurality of outer holes and a bar-shaped innerend extending along a longitudinal axis from the outer end and formedwith a plurality of inner holes, the plate being adapted to be screwedthrough the outer holes to the epiphysis and through the inner holes tothe diaphysis, the plate further being formed on the bar-shaped innerend with a longitudinally extending throughgoing guide slot and betweenthe guide slot and the outer holes with an aperture of a predeterminedtransverse width and of a longitudinal length generally equal to alength of the guide slot; a slide having a longitudinally extending legwith an inner end formed with a guide formation engaged into andlongitudinally slidable along the guide slot and a crosspiece overlyingthe aperture and of a transverse width at least equal to the transversewidth of the aperture such that crosspiece engages the bone plate toboth transverse sides of the aperture, the crosspiece being formed witha transversely elongated slide slot; and a slide screw engaged throughthe slide.
 2. The assembly defined in claim 1 wherein the adjuster isT-shaped.
 3. The assembly defined in claim 1 wherein the aperture isgenerally triangular or trapezoidal.
 4. The assembly defined in claim 1wherein the outer part of the bone plate lies generally in a planeforming a small acute angle with a plane of the inner part of the boneplate.
 5. The assembly defined in claim 4 wherein the angle is between5° and 15°.
 6. The assembly defined in claim 1 wherein the guide slothas a length of between 6 mm and 12 mm.
 7. The assembly defined in claim1 wherein the transverse width of the slide slot is between 12 mm and 14mm.
 8. The assembly defined in claim 1 wherein the aperture has an openarea equal to between one-half and four-fifths of the length of thediaphysis at the fracture.
 9. The assembly defined in claim 1 wherein ahead of the slide screw bears toward the bone on the adjuster andpresses the adjuster against the bone plate.
 10. The assembly defined inclaim 1, further comprising: a tool filtrable against the outer part ofthe bone plate and formed with holes alignable with the outer holes fordrilling holes through same and fitting screws into the drilled holes.11. A method of reducing a fracture between an epiphysis and a diaphysisof a bone, using an assembly having: a bone plate having a fan-shapedouter end formed with a plurality of outer holes and a bar-shaped innerend extending along a longitudinal axis from the outer end and formedwith a plurality of inner holes, the plate further being formed on thebar-shaped inner end with a longitudinally extending throughgoing guideslot and between the guide slot and the outer holes with an aperture ofa predetermined transverse width and of a longitudinal length generallyequal to a length of the guide slot; a slide having a longitudinallyextending leg with an inner end formed with a guide formation engagedinto and longitudinally slidable along the guide slot and a crosspieceoverlying the aperture and of a transverse width at least equal to thetransverse width of the aperture such that crosspiece engages the boneplate to both transverse sides of the aperture, the crosspiece beingformed with a transversely elongated slide slot; and a slide screwengaged through the slide slot and through the aperture with thediaphysis, the transverse width of the aperture being substantiallygreater than the slide screw such that the bone plate can movetransversely relative to the slide screw, the method comprising thesteps of sequentially: screwing the outer part to the epiphysis throughthe outer holes to anchor the bone plate to the epiphysis; screwing theslide screw through the slide slot and aperture into the diaphysis; andshifting the bone plate and the epiphysis it is anchored tolongitudinally relative to the diaphysis with sliding of the pivotformation in the guide slot to reduce the fracture and transverselyrelative to the diaphysis with to correct transverse offset of thediaphysis and epiphysis at the fracture.